Eretria, Greece offers 5 beaches perfect for sunbathing, surfing, swimming, and more. Eretria is known for the Archaeological Museum of Eretria and the ancient ruins of the Temple of Apollo. The best time to travel to Eretria, Greece, is from May to September, with average air temperatures around 75-85°F (24-29°C) and water temperatures around 72-79°F (22-26°C). Sandee provides detailed maps, photos, and reviews from fellow beachgoers to help you Choose Your Beach™ and plan your perfect beach vacation!